A. Field of Invention
The present invention relates generally to railroad cars and, and more particularly to a new and improved railroad car truck holding the wheels and supporting the railroad car body relative to the wheels.
B. Description of Related Art
An important design goal for railway freight cars particularly, for bulk train service, is the reduction of the tare weight of the vehicle itself. Thus the car can carry an increased weight of lading on each load trip for a given reduction in tare weight where car operation is at the maximum allowable weight on rail as determined by the wheel bearing size.
Considerable progress has been made in the reduction of the weight of the body of rail cars, particularly in the case of the high utilization coal car, with the use of aluminum construction. Relatively less progress has been made, however, in the reduction of the weight of the conventional four-wheel rail car truck which comprises the structure by which the rail car body is supported relative to the wheels. Generally, each rail car is supported by two truck assemblies, with one at each end of the rail car, and each truck assembly comprises two wheelsets comprising a pair of wheels and the axle therebetween. Since the two truck assemblies must bear the entire weight of the rail car body and load, the truck assemblies are substantial and approximately one-half of the total rail car tare weight may be contributed by the truck system. A factor commonly contributing to the overall weight of conventional truck systems is the need to allow the truck to pivot relative to the rail car body in order to allow the wheels to follow curving tracks. The need to support the entire load at the two pivot points, dictates that the supporting frame and bolster members on the rail car truck and on the rail car body must be quite substantial, and therefore, quite heavy.
IV. SUMMARY OF THE INVENTION
This invention presents a design of a rail car truck for maximum reduction of the weight of that component. The present invention comprises a railroad car truck assembly having a radial side mounting support of the car body permitting the truck to swivel relative to the car body while transmitting axle loading in a direct load path to the car body. The truck assembly comprises a lightweight truck frame without a heavy central bolster member such as is commonly used to support a center pivot point in a conventional truck. The rail car body is supported above each of the four wheelset journal bearings by a flat, arcuate, horizontal and upward facing support member which is supported by the truck frame. The rail car body, at each end comprises four corresponding arcuate channel members sized and shaped to receive the truck mounted support members and having a flat, horizontal and downward facing surface in the same shape as, but longer than, the truck mounted support member surfaces.
A non-load bearing pivot sleeve is mounted in the center of the truck frame and is formed to receive a pivot pin extending downward from the underside of the car body. The distance from the central pivot point determines the radius of curvature of the edges of the support surfaces as well as the channel members such that the truck assembly is able to swivel about the pivot point while the support member surfaces are engaged within the channel members. A minimal radial clearance between each support member edge and channel member flange allows the engagement of the pivot pin within the pivot sleeve to restrain the horizontal displacement of the truck which has only a range of rotational movement relative to the car body. The arc contained by the channel members being longer than the arc of the support members, a limited range of rotational movement relative to the car body is permitted. The opposing support surfaces are formed of substances that provide durable wear and as little sliding friction as possible.
The improved rail car truck of the present invention includes improved spring assemblies. The wheel set axles are received in journal bearings that are in turn retained within saddle assemblies which are in turn received within the truck frame. The saddle assemblies provide lower spring support surfaces that secure the lower ends of two pairs of springs, the upper ends of which springs engage opposing surfaces on the truck frame. For each wheelset bearing, the springs of one of the two spring pairs are longer than the other springs such that when the car is empty, only the two longer springs engage and are compressed between the truck and saddle assembly. In this manner, the unloaded car is suspended by an appropriately softer suspension load, while the fully loaded car is suspended by both spring pairs for a stiffer suspension.
Each wheelset saddle is aligned within the frame by means of a truck stabilizing wedge block member which comprises a generally wedge shaped member with a vertical surface that engages an opposing surface on the saddle normal to the direction of travel and an inclined surface that engages an opposing inclined surface on the truck. The bottom of the wedge member engages one of the longer springs which urges the wedge member upward against the inclined surface and the interaction of the two opposing inclined surfaces causes the wedge member to slide forward against the vertical surface of the saddle. The resulting single side arrangement of the stabilizing wedge block members acting on wheelset saddles tends to hold the saddles and thus the wheelsets in a squared and parallel relationship within the truck frame assembly. An elastomeric wheel bearing adapter mounting is placed between the top of the wheelset bearing and the saddle to give the truck a radial turning capacity for curving as well as a form of primary suspension for added ride cushioning.
The different truck design features combine to form a unique primary suspension and support system functioning effectively to permit truck swiveling while providing an essentially direct load path from each of the wheelset axle journal bearings to the rail car body. The present invention permits minimum truck frame structure and weight and thus the weight of the entire truck assembly is minimized. Also accomplished by the resulting truck assembly are other design goals for improved freight car trucks in general, e.g., improved ride, increased wheelset hunting control, and reduced wheel wear.
The principal aim of the present invention is to provide a new and improved railroad car wheel truck which meets the foregoing requirements and which is lighter than conventional wheel trucks.
Another and further object and aim of the present invention is to provide a new and improved railroad car wheel truck which meets the foregoing requirements and which will be compatible with conventional rail car bodies.
Yet another and further object and aim of the present invention is to provide a new and improved railroad car wheel truck which meets the foregoing requirements and which also meets the necessary truck performance requirements when the car is empty.
Other objects and advantages of the invention will become apparent from the Description of the Preferred Embodiments and the Drawings and will be in part pointed out in more detail hereinafter.
The invention consists in the features of construction, combination of elements and arrangement of parts exemplified in the construction hereinafter described and the scope of the invention will be indicated in the claims.